Nowadays, the bicycle has become a type of widely used vehicle and a type of most popular goods for sports and leisure activities. For a traditional bicycle, the bicycle is generally further installed or placed with an object on a frame thereof, for enhancing the function of the bicycle and the usage convenience of the object. Especially, a bottle cage can be installed on the frame without affecting riding, for placing a water bottle and conveniently taking it, so that a bicycle rider can take the water bottle for drinking.
Referring now to FIG. 1, an operational view of a traditional bottle cage of a bicycle is illustrated, wherein the bicycle comprises a frame 91, a bottle cage 92 and a water bottle 93. The frame 91 is formed with two screw holes 911. The bottle cage 92 is a hollow bent bracket with a substantial L-shape, and two screwing elements “a” are passed through two through holes (not shown) of the bottle cage 92 and the two screw holes 911, so that the bottle cage 92 can be screw-connected to the frame 91. The bottle cage 92 can suitably receive a water bottle 93 which is placed from top to bottom. The water bottle 93 is retained by the bottle cage 92 without being separated from the bottle cage 92, and the water bottle 93 can be optionally taken, placed and used by the bicycle rider.
However, there are still several disadvantages existing in the bottle cage 92 during actual operation, as follows: (1) the bottle cage 92 is directly in contact with the water bottle 93. When the water bottle 93 is taken and placed or is vibrated during riding the bicycle, the material or printing on the surface of the water bottle 93 is easily worn, so as to affect the texture and appearance of the water bottle 93; (2) when it is unnecessary to mount the water bottle 92 on the frame 91, the bottle cage 92 is still mounted on the frame 91, so as to affect the simplicity of the appearance of the bicycle; and (3) it is unsuitable for a foldable bicycle to install the bottle cage 92, because the bottle cage 92 will affect the foldable function of the foldable bicycle.
As a result, it is necessary to provide a fastening device for a bicycle to solve the problems existing in the traditional technology, as described above.